1. Technical Field
The present invention relates to a peripheral rewinding machine for producing rolls of wound web material, comprising: insertion means for sequentially inserting winding spindles into a winding area; winding means, in said winding area, which wind predetermined quantities of web material onto the spindles; extraction means for extracting said spindles from the rolls of web material formed on them; and recirculation means for returning the spindles extracted from said rolls toward said insertion means.
The spindles may be caused to rotate by the winding means, or may be initially made to rotate by suitable members acting on them independently of the winding means.
The present invention also relates to a method for producing rolls of web material, comprising the stages of inserting a winding spindle into a winding area; winding a predeterminable quantity of web material on said winding spindle to form a roll around said winding spindle; and extracting said winding spindle from the roll.
2. Background Art
At the present time, the winding of web material for producing rolls is preferably carried out by means of rewinding machines of the peripheral type, in other words those in which the rotary motion for the winding is provided by members which act peripherally on the roll being formed. Examples of rewinders of this type are described, for example, in GB-A-2105688, U.S. Pat. Nos. 4,487,377, 5,249,756, 5,248,106, 5,137,225, 5,368,252, 5,639,046, 5,538,199, WO-A-9421545. These peripheral rewinders are of the continuous and automatic type, in the sense that they produce finished rolls in an automatic sequence, causing the interruption of the web material at the end of each winding operation and thus the formation of a tail edge of the finished roll and a leading edge of the following roll.
In some rewinding machines of known type, the winding is done on tubular winding cores or spindles, made from cardboard or similar, which remain inside the roll. In other machines of more recent design, the winding is done without a tubular winding core, as described for example in U.S. Pat. No. 5,639,046 or in U.S. Pat. No. 5,538,199. With these machines a compact roll without a central hole is produced. This makes it necessary to use special feeders for the use of the material.
IT-B-1201390 describes a peripheral rewinder in which the rolls are produced by winding on tubular spindles which are subsequently extracted from the formed roll. In this way, each roll has no central tubular core but has a hole for the insertion of a support typically used in feeders of material in roll form, for example feeders of kitchen paper, toilet paper or similar. This machine has the disadvantage that the extraction of a relatively long spindle from the roll requires a considerable tractive force to overcome the friction. Furthermore, the sliding of the whole length of the spindle inside the roll causes deformations of the inner turns of the wound web material.
The present invention relates to an improvement to peripheral rewinding machines with extractable winding spindles, of the type described, for example, in IT-B-1201390.
Essentially, the rewinding machine according to the invention is characterized in that the winding spindles are made in two portions which can be connected and disconnected; in that the extraction means extract each of said two portions from a corresponding end of the corresponding wound roll; and in that means are provided for reconnecting said two portions to each other so that said spindles can be reinserted into said winding area.
In this way, each portion of spindle has to travel for a shorter distance inside the roll to be extracted from it. The extraction means also have to travel for a shorter distance, and this enables the lateral dimensions to be limited, resulting in a greater ease of laying out the converting line.
This is particularly important because the present tendency in the field of the paper converting industry is to produce parent rolls of increasing length, with a consequent increase in the width of the rewinding lines. Furthermore, if two portions of spindle, each having a length approximately equal to half the length of the spindle, have to be extracted, this will yield a balancing and a reduction of the stress and a reduction of the deformation of the inner turns of the wound material.
In a possible embodiment of the invention, the extraction means used to extract the winding spindle are associated with two conveyers which extend laterally with respect to the winding area on both sides, to return the two portions of each spindle separately toward said insertion means, said means for reconnecting the two portions of said spindles to each other being located before the winding area. There is no reason why the two portions of spindle should not be connected before they are returned toward the insertion area, for example under the extraction area. In this case, it is possible to provide a single conveyer under the area of extraction of the two portions of spindle.
In a particularly advantageous embodiment, the conveyers comprise recirculation runways for returning the portions of said spindles, along which the portions of spindle roll by gravity.
The two portions of each spindle can be connected to each other by snap-fitting or other means. However, in a preferred embodiment, they have, at the ends to be connected, complementary conical surfaces which are used for the axial alignment of the two portions. Their detachment from each other can easily be prevented by positioning lateral containing walls along the spindle insertion path. When the winding has started, the two portions of spindle are held together by the turns being wound and by the contact with the winding members.
The method for producing rolls of web material according to the invention comprises the stages of inserting a winding spindle into a winding area; winding a predeterminable quantity of web material on said winding spindle to form a roll around said winding spindle; and extracting said winding spindle from the roll. Characteristically, according to the invention it is provided that said spindle is divided into two portions; said two portions are connected before the start of the winding of said web material on them; and the two portions of spindle are extracted separately from the two opposite ends of the roll wound on them.
Further advantageous embodiments of the invention are indicated in the attached claims.